1. Field of the Invention
This invention relates to an image reading device for use in, for example, a facsimile apparatus, and more particularly to an image reading device in which two or more reflection mirror holders are provided on a mirror frame so that a reflection mirror can be located at two different positions and angular orientations. This, in turn, allows the image reading device to utilize two or more types of condenser lens units for focusing a light beam on a reading device.
2. Description of Related Art
FIG. 5A is a sectional side view of an image reading device used in a facsimile apparatus shown in FIG. 5B. As shown in FIG. 5A, a document P inserted from a document inlet 61 is fed by feed rollers 62 and an image on the surface of the document is read by an image reading device 50 at an image reading position Q while the document is pressed by a document presser 63 to remove its slack. The image reading device 50 comprises a light emitting unit 51, a first reflection mirror 52, a second reflection mirror 53, a condenser lens unit 54, and a light receiving unit 55.
The light emitting unit 51 is provided with a plurality of linearly arranged light emitting elements. A light beam is emitted from the light emitting elements onto the document P, and the light beam is reflected from the surface of the document P to generate a reflected light beam R for reading. The reflected light beam R enters a cylindrical condenser lens unit 54, having one or more condenser lenses 54A, via the first reflection mirror 52 and the second reflection mirror 53. The first and second reflection mirrors are mounted on a mirror frame 56. The reflected light beam R is condensed onto the light receiving unit 55 by the condenser lens unit 54, and thereby an image on the document P is formed on the light receiving unit 55.
The light receiving unit 55 is provided with a plurality of linearly arranged charge collecting devices (CCDS), each of which outputs a voltage corresponding to the intensity of the reflected light beam R entering the light receiving unit 55. Thus, when the reflected light beam R is condensed on the receiving unit 55, the image on the document P is read as electrical signals. The document P from which the image has been read is fed to discharge rollers 64 and discharged from a document outlet 65 to the outside of the facsimile apparatus.
As described above, the reflected light beam is required to enter the light receiving unit 55 accurately to read the image on the document P. For this purpose, the reflection mirrors 52 and 53 and the condenser lens unit 54 are mounted accurately at predetermined angles in their mounting positions on the mirror frame 56.
The condenser lenses 54A used for the condenser lens unit 54 vary in a distance between an object and an imaging point, and in their outside diameter, depending on the type and manufacturer. As a result, there has been a problem in that two or more types of condenser lens units 54 cannot be used on one type of mirror frame 56, and a mirror frame 56 must be prepared for each type of condenser lens unit 54.